There are a Bronze Age ring cairn and cairn upon the slopes of Pen Trumau. According to Coflein:
Bronze Age Cairn I - SO1963729254:
'Cairn I at Pen Trumau is a stone cairn, 20m in diameter and up to 2m high, on the edge of a natural terrace below Pen Trumau. Turf and bilberries covered the edges but most of the cairn was clear of vegetation when recorded in November 2007. The centre of the cairn was disturbed. Two modern cairns surmount it.'
Bronze Age Ring Cairn - SO1963429242:
'Lying 1m to the south side of Bronze Age cairn was a small irregular sub circular feature, approximately 6.3m x 4.2m, defined by a stone bank 1m wide x 0.3m high'.